1. Field of the Invention
The present invention relates to a water based hydraulic fluid used in a hydraulic pressure device having a sliding portion of a member constructed by an iron-based material, and a hydraulic pressure device having the sliding portion of the member constructed by the iron-based material and using the water based hydraulic fluid.
2. Description of the Related Art
For example, an hydraulic fluid of a mineral matter oil is normally used conventionally in a system for operating a working machine by the hydraulic fluid supplied by a pump.
However, a using place of the hydraulic fluid of the mineral matter oil is limited since this hydraulic fluid is easily burned. There is also a fear that environment is polluted in leakage of the hydraulic fluid. Further, the hydraulic fluid of the mineral matter oil has high viscosity so that there are disadvantages in that energy loss is caused at operating times of the pump and the working machine.
Therefore, a water based hydraulic fluid such as a water-glycol hydraulic fluid or a water-emulsion hydraulic fluid, etc., is provided in these days as an hydraulic fluid which can solve the above disadvantages.
In the hydraulic pressure device such as the pump, the working machine, etc., each of constructional parts is generally manufactured by an iron-based material, i.e., a material such as carbon steel, chromium steel, etc. in which an alloy element such as carbon, chromium, etc. is contained in iron as a main raw material. However, when the water based hydraulic fluid is used as the hydraulic fluid of these hydraulic pressure devices, an oil film formed in a sliding portion of members such as a supporting portion of a rotating shaft, an engaging portion of a gear, etc. is thin so that the iron-based materials are inevitably burned and worn by metallic contact.
In consideration of the above actual situation, the present invention is aimed to provide a water based hydraulic fluid and a hydraulic pressure device which can prevent burning and wearing in a sliding portion of a member constructed by an iron-based material as much as possible.
To achieve the above aim, the invention according to a first aspect resides in a water based hydraulic fluid used in a hydraulic pressure device having a sliding portion of a member constructed by an iron-based material, wherein the water based hydraulic fluid contains metallic ions for forming a film on a surface of the member constructed by said iron-based material.
In accordance with the water based hydraulic fluid of the above construction, the film can be formed on the surface of the member constructed by the iron-based material. Accordingly, it is possible to prevent sliding due to metallic contact of the member by this film so that burning and wearing in the sliding portion of this member can be prevented as much as possible.
The invention according to a second aspect resides in a hydraulic pressure device having a sliding portion of a member constructed by an iron-based material and using a water based hydraulic fluid, wherein the water based hydraulic fluid contains metallic ions for forming a film on a surface of the member constructed by said iron-based material.
In accordance with the hydraulic pressure device of the above construction, the film is formed by the water based hydraulic fluid on the surface of the member constructed by the iron-based material. Accordingly, it is possible to prevent sliding due to metallic contact of the member by this film so that burning and wearing in the sliding portion of this member can be prevented as much as possible.